They won't ban you. The reason they discourage exploring areas like this is to reduce ticket times because people tend to get stuck in them by falling through the world or the unstuck trick. Not sure if it still works (probably not) but, you used to be able to travel through some invisible walls by using the unstuck button feature, but you had to destroy your hearthstone or it would just hearth you. Both the unstuck trick and falling through the world result in people putting in GM tickets to save their character.

Actually it is.
There is nothing underneath Orgrimmar.
KC is an actual place put into the client. If they didn't want people to go there, then they would just remove it.

Eep you clearly don't understand much do ya, You're -not-supposed to go there, that's why there isn't a door you can walk in, Just because something's there doesn't mean it's for you to go to xD Some people:P

I doubt you will get in trouble, but it is likely, i know of people have that have been giving 3hrs for it, But personaly I've never had anything and I've been in alot of "forbidden" areas over the years=D

I doubt that. I've been there many times, and I and my guild were even playing hide-and-seek in there, and nobody got banned.
Actually, I even was on GM island once (without modifying client, just in-game methods like nitro boots), and still - no ban.
So as long as you don't spam day and night "sell access to crypts for gold", you are ok.

Eep you clearly don't understand much do ya, You're -not-supposed to go there, that's why there isn't a door you can walk in, Just because something's there doesn't mean it's for you to go to xD Some people:P

Really?...really?
So they still keep Crypts in game because people are not suppose to go there?
Crypts is not a bug that lets you kill people from inside a wall. Crypts is an Easter egg and they keep it in the game on purpose.

I dont know if this helps but ive been in places i shouldnt be in back in the days. I used to find a mountain wall where i could spam jump until i succeeded climbing a bit. Then i spammed jump button for the next step and continued until i "bugged" myself up and explored the place. i found lots of weird stuffs and ive been chatting with GMs while going on a trip and i didnt get banned for it.

I also went to Gilneas but a GM told me thats not a place i should be in because propably if you abuse the release system to get to a place you might get hurt but idk. I havent been in that place yet but ive heard you need to use the help system to get there? If you dont have to use it and just do it yourself normally i dont think you can get banned for it, that would be silly.

Funny story - this one time I was jumping in ZG to try get underneath it to fly to Karazhan, just as I got into the "underground altar" bit a GM appeared and was all like
"Greetings! Not doing anything suspicious I hope?"
Insta reaction? Fuck, I'm suspended. May as well tell the truth.
"Just going to go look at the Karazhan Crypts, saw a video of it on YouTube, looks interesting."
"Hmm, I see. Well, we can't have that, sorry."
Boom, teleported out. Nothing else was said.
Never tried going there again.

People have been in there before and nothing bad happened to them. As long as you don't hack they could care less.

Also, to the people saying "why is it in there if you're not supposed to be there"... It's there because it was going to be apart of the game. You don't go back in and recode the game to take out something so small. It would be a waste in resources to take it out, and they might actually want to revisit it someday in the future.

People have been in there before and nothing bad happened to them. As long as you don't hack they could care less.

Also, to the people saying "why is it in there if you're not supposed to be there"... It's there because it was going to be apart of the game. You don't go back in and recode the game to take out something so small. It would be a waste in resources to take it out, and they might actually want to revisit it someday in the future.

At least someone knows why it's still there, People who claim it's an easter egg and you're supposed to exploit to get into it are more deluded than i thought lol
But as alot of people have said, Blizz are very lenient as long as you're not doing anything too dodgy, or gaining an upper hand over someone else

Also, to the people saying "why is it in there if you're not supposed to be there"... It's there because it was going to be apart of the game. You don't go back in and recode the game to take out something so small. It would be a waste in resources to take it out, and they might actually want to revisit it someday in the future.

You don't have to recode the game in order to remove assets. Also they did revamp the whole Azeroth back in Cata yet they didn't take Kara Crypts out. Again, they are keeping Crypts on purpose.

I've been to old Outland through the old deadmines by abusing the priest levitate bug.
I abused same bug to go above orgrimmar before cata.
I've been in the crypts before (love the place) using a bug where mounting and jumping at the same time would force you through walls so you could fly underground.
Same thing made it possible to get in next to the ah goblins in orgrimmar.
I've been in old Gilneas before cata (there were nothing. A big flat area....)
Tried to get into Hyjal before cata but you'd get kicked out :P
I were in uninstanced version of ZG pre cata re-release for the luls of it.

I'm sure i've been loads of other place but these are the things i cant remember right at this moment.

This is the kind of things that adds flavour to the game once you're able to say been there, done that to most things.